Centrifugal casting



June 12, 1934.

L. H. BROWN CENTRIFUGAL CASTING Original Filed June 7, 1929 dif INVENTOR LUCIAN H. BROWN BY i ATTORNEY Patented June 12, 1934 UNITED STATES PATENT OFFICE Haynes Stellite Indiana Company, a corporation of Original application June '1, 1929, Serial No.

369,208. Divided and this application November 17, 1932, Serial No. 643,026

4 Claims.

This invention pertains to the centrifugal casting of alloys that melt at temperatures upwards of about 1700 C. The present application is a division of an application filed on June 7, 1929,

5 bearing Serial Number 369,208, Patent Number 1,924,976 and is directed specifically to a process for casting such alloys.

Alloys that melt at extremely high temperatures tend to freeze so quickly when the source of heat is removed that it is impossible to handle them in ladies like low melting alloys, or even to pour them directly from the crucible in which they are melted into stationary molds and secure good castings. Therefore, in order to pro- 5 duce good castings from such an alloy it must be transferred from the crucible to the mold instantly and in addition pressure must be applied to force it into the mold.

Such pressure may be most readily produced in the form of centrifugal force applied in the manner practiced in the art of centrifugal casting, but centrifugal casting methods that are applied to metals having a low melting point are impractical when applied to metals having a high 5 melting point because too much time is spent in getting the metal from the furnace into the mold. This is especially true when casting alloys high in tungsten such as those having a composition of w- 70.0 to 95.0%- C .5 to 6.0% Other metals 0.0 to 25.0%

The invention therefore includes a process of casting high-melting alloys, for example tungsten carbide compositions, which comprises fusing the said alloy, maintaining it in the fused condition by the application of heat until the instant it is poured, and pouring it instantly into 40 a relatively cool mold. Preferably the heating is effected by an electric arc, and the arc in turn preferably is maintained chiefly between a carbon electrode and the surface of the alloy. It is also particularly advantageous to employ a rapidly rotating mold.

The invention will be described in detail in connection with the apparatus shown by the accompanying drawing wherein one form of suitable apparatus is shown. It is clear however that the process of the invention is quite independent of any specific form or kind of apparatus, and is not to be construed as limited thereto in any manner. In the drawing,

Figure 1 is a side elevation of one embodiment of a suitable casting machine with portions thereof cut away to show the interior construction of the furnace and the position of the crucible and mold therein at the time of casting; I

Figure 2 is a plan view of the casting machine 10 of Figure 1 with the mold and its supporting and rotating mechanism swung to one side in the position it occupies while the alloy is being fused; and

Figure 3 is a horizontal section of a suitable mold as in Figure 1.

Referring to the drawing, the casting machine may comprise a furnace 10 having a crucible 11 that is adapted for holding the ingredients of an alloy while they are being fused by an electric arc from an electrode 12, and a rotatable mold 13 into which'the molten alloy may be cast instantly by tilting the entire machine as a unit on its supporting trunnions 14. The path of the electric current may be from a conductor 15 through a conductor 25 carried by and insulated from an electrode holder 16, the electrode 12, the crucible 11, the furnace 10 and a conductor 21. The mold 13 may be rotated by an electromotor 1'7 through a mold-supporting shaft 18 and convenient driving connections. The motor 17, mold-supporting shaft 18, and the driving connections between them may be mounted on a table 22 pivoted on a bracket 23 on the furnace 10, whereby the mold 13 may be swung into and out of position adjacent a pouring aperture or spout 20 of the crucible 11. A latch 24 to hold the table 22 in position for pouring may also be desired. The furnace 10 and mold 13 may be rotated on the trunnions 14 by means of a convenient handle 19.

The operating cycle of the casting machine shown in the drawing may be completed in less than one minute and the sequence of operations may be substantially as follows: the ingredients of an alloy are placed in the crucible 11, and electric current is connected to conductors 15 and 21. While the ingredients of the alloy are being fused, which requires only about 35 seconds/the sprue of the cold mold 13 is brought opposite the pouring aperture 20, the electromotor 17 is started, and the mold 13 rotated by the electromotor 17. The casting operation is performed by an operator who grasps the handle 19 and tilts the entire casting machine on its trunnions 14 so 05 that the molten alloy in crucible 11 is poured out through the aperture 20 into the rotating mold 13. When the casting machine has been tilted about 90 degrees the electric current is disconnected from the electrode. Asthe mold is comparatively'cold the alloy hardens instantly; therefore, after pouring, the casting machine is immediately returned to an upright position, and the mold 13 is then promptly removed from the casting machine. 9

The castings produced by this improved casting process are well formed and free from holes or other defects. Drawing dies, tool tips, etc., may be cast very closely to size, thus materially reducing the labor required to finish them.

Various alterations and substitutions may be made in the construction and arrangement of the centrifugal casting machine without departing from the spirit of the invention. 7

I claim:

1. The process of casting alloys which contain substantial amounts of tungsten and which melt at temperatures upwards of about 1700" C. coinprising fusing said alloy, maintaining it in the fused condition by the application of heat until the instant it is poured, and pouring it directly into a relatively cool rotating mold.

2. The process of casting alloys which contain substantial amounts of tungsten and which 'meit at temperatures upwards of about 1700* C. comprising fusing said alloy by an electric arc, maintaining it in the fused condition by said are until the instant when said alloy is poured, and

pouring said alloy directly into a relatively cool LUCIAN H. BROWN. 

